Textile treatment



from such fabrics.

Patented Feb. 16, 1943 Paul S. Pinkney, Wilmington, Del., assignor to E.I. du Pont do Nemours & Company, Wilmington,Del., a corporation ofDelaware .No Drawing. Application November 8, "1940,

. Serial N0. 364,886

8 Claims.

This invention relates to the treatment; with formaldehyde of textilematerials which are reactive thereto. More particularly, it relates to aprocess for increasing the uniformity of reaction betweenformaldehydeand a textile material.

The term textile material is intended to include filamentaflbers, stapleor yarns, whether in the finished stage or at someinte'rmediate stage inthe production thereof.- The term also includes fabrics, whetherknitted, woven. or

felted, as well as, garments or other articles made It has long beenknown to react textile materials with formaldehyde. Such reaction hasbeen carried out for thepurpose of increasing the strength of textilesor to improve their resilience, crease resistance, crush resistance,crimp retention, resistance to shrinking, and to reduce the dry and ,wetelongation and the extent to which such materials are swelled by water.

Many of thesepreviously known processes have been unsuccessful due tothe non-uniformity of \treatment or the embrittlement of the textile.

Processes used heretofore for treating textile materials withformaldehyde have involved treating the impregnated textile material ina hot-air chamber or on a drying cylinder. drying cylinders isapplicable only to flat fabrics which are not too'thick for efficientheating.

Heating in a hot-air chamber is not satisfactory for yarn, rope, orstaple, or for garments, because uniformity of treatment cannot beobtained unless heating is continued until all parts of the textilematerial have reacted to a maximum extent with the formaldehyde. Thisleads to extreme brittleness.

difficult to obtain uniformity of treatment due to the more markedeffect of unevenness in the extent to which formaldehyde is lost byevaporation from the various portionsofthe textile material. When theheating period is reduced,

the less exposed portions of the textile material are likely to bemarkedly undertreatedi It is, therefore, an object of the presentinvention to provide a process for reacting a textile materia1 withformaldehyde with great uniformity and without objectionableembtrittlement.

It is another object of the present invention to provide a process foruniformly reacting a textile material with the minimum quantity offormaldehyde to accomplish the desired effect.

Treating on Other objects of the invention will appear hereinafter. e

The objects of'this invention may be accomplished, in general, byimpregnating a formaldehyde-reactive textile material with the desiredquantity of an aqueous solution of formaldehyde together with anacid-reacting catalyst, drying the impregnated material and heating thesame to the desired reaction temperature by immersirig the same in ahot, substantially anhydrous liquid which is substantially inert towater; i. e., which is not hydrolyzable.

The following examples illu'strate in great detall, the preferredmethods of carrying out the process of this invention. It is to beunderstood, however, that the present invention is not limited to thespecific details set forth therein,

1 EXAMPLE I Skeins of l50-denier, IO-filament, 2.8-turns per inch twist,bright unfinished viscose rayon yarn are impregnated with a watersolution containing the amounts of formaldehyde and ammo'nium chlorideindicated in Table I. The saturated skeins are centrifuged to removeexcess solution, and immersed in boiling benzene for 1 hour. Water isdistilled with the benzene during this heating step so that the yarn is,in effect, dried and then heated under substantially anhydrousconditions. The skeins are centrifuged, dried at room temperature,treated with a 1% aqueous ammonium hydroxide solution at 50 C. for 5minutes, rinsed, and dried. Results I When lower concentra- Y tions offormaldehyde are usedfit is even more of this treatment are summarizedin Table I:

Table I i I s e mmoncrease onga on Formal Crease in wet nirnn dehydechloride angle strength Wet Dry 7 Per cent Per cent Degrm PercentPercent Percent Control.- None None C 4.0.12 99 lii""8 7 When thetreated yarns are dyed with du Pont Pontamine" Sky Blue 632! (Rowe ColorIndex No. 518), a direct cotton dye, it is very apparent that the yarnineach sk'ein is uniformly modifled throughout the skein. The affinityof viscose rayon for direct cotton dyes is lowered by treatment withformaldehyde to an extent which varies with the severity of thetreatment. Thus, when part of a skein is more heavily treated withformaldehyde than the rest of theskein, it is dyed much lighter than therest of the skein. Unevenness of this nature is very apparent when askein of viscose rayon yarn is dyed after being treated with an aqueoussolution containing 8% of formaldehyde and 0.25% of ammonium chloride,centrifuged, dried at 65-70 C. for 2 hours, an baked at 150 C. for 3'minutes.

Crease angles of yarn of this type are determined by winding singlethreads over a doubleedged lmife blade under a tension of 50 grams,removing the tension after 15 minutes, cutting the thread along one edgeof the knife, and determining the average angle of crease of about 10 ofthe resulting short lengths of thread after a relaxation period of 10minutes. An increase in crease angle indicates improved resilience.

Exmu: II

A skein of viscose rayon. yam like that treated in Example I isimpregnated with a water solution containing 3% of formaldehyde and 0.4%of ammonium chloride, centrifuged, dried at room temperature, immersedin xylene at 138' C. for 2 minutes, rinsed with methanol treated for '3Exlmru III A skein of viscose rayon yam like that treated in Example Iis impregnated with a water solution containing 3% of formaldehyde and0.4% of ammonium chloride, centrifuged, and dried at room temperature.It is immersed for 2 minutes in bis(methoxyethoxyethyl) ether at atemperature of 138 C. The treated yarn shows uniformly improvedresilience. Butoxyethoxyethyl acetate can be used as the liquid heatingmedium with the same advantageous results. Y

EXAMPLE IV There are described in U. S. application Serial No. 318,326,filed February 10, 1940, by William D. Nicoll, new high tenacity crimpedregenerated cellulose filaments and fibers and a process for producingthem which comprises the steps of spinning filaments from a viscosesolution into a single coagulating and regenerating bath and relaxingthe filaments, free from tension, in an aqueous liquid, said steps beingcarried out in accordance with certain critical relationship factorslisted in the application. ,A skein of yarn prepared by this process isimpregnated with a water solution containing 3% of formaldehyde and 0.4%of ammonium chloride, centrifuged, and dried at room temperature. It isimmersed for 1 minute in xylene heated to 138 C. and washed according tothe procedure used in Example 11. The crease angle of the yarn isincreased by this treatment from 86that of the untreated yarnto 133";

its wet, strength is increased 14%; and its elongation, both'dry andwet, is lowered. The treated yarn shows uniformly improved crimpretentivity and resistance to swelling by water. Non-uniformmodification of a skein of this yarn treated similarly except that it isheated in air is quite apparent when the yarn is dyed.

EXAMPLE V High tenacity viscose rayon yam prepared by the processdescribed in U. S. Patents Nos. 2,083,252 and 2,133,714 is wound on abobbin, impregnated with a water solution containing 5% of formaldehydeand 0.5% of ammonium chloride, centriffi'ged, and dried at roomtemperature. It is immersed for 30 seconds in xylene, rinsed withbenzene, dried,.washed with a warm 1% rinsed, and dried. The improvedresilience of the 15 yarn treated in this manner is shown by the rise increase angle from l13-that of the untreated yarnto 133. The treated yarnshows lowered elongation and improved resistance to swelling by water.Yarn of this type treated similarly except that it is heated in air ismarkedly less uniformly modified.

ExAurtr: VI

Skeins of the new crimped viscose rayon yarn 5 (2,500-denier,100-filament, 2-turns per inch 'twist) described and claimed in U. S.application Serial No. 180,976, filed December 21, 1937, by William HaleCharch and William Frederick Underwood, are treated according totheprocedure of Example I. This new yarn is produced as described andclaimed in the above application by the extrusion of viscose into a;coagulating bath having a rapid coagulating action and a slow, or no,regenerating action with a velocity of extru- $1021 at least 4 times thevelocity of draw-off. The streams of viscose issuing from the spinneretinto the coagulating bath under the aforementioned conditionsspontaneously assume a finely crimped form which persists as a permanentstructural characteristic in the filaments. The resulting yarn iscomposed of substantially non-crenulated filaments having an inherentand'substantially permanent crimp, the crimps in the several filameritsof the yarn being out of phase with each other. The filaments exhibitsubstantially no orientation in the direction of the fiber axis.

Results of the formaldehyde treatment are summarized in Table II. Thefigures given in the table to represent the changes in propertieseflectedby the treatment are, of course, with reference to untreatedyarns.

Table II De- De- Decrease crease Form- Ammo- Increase in sponin aldeniumCrease crease in taneous secondhyde chloride angle in wet elongaextenarystren th tion 'sion swellwhen ing wet C o n Per cent Per cent DegreesPer cent Per cent Per cent Per can! trol None None 66 A 13 0. 4 180 135100 80 B. 8 0. 129 144 37 63 74 C. 4 0.12 76 47 42 46 49 Crease anglemeasurements on the yarn are made in much the same manner as describedin Example I except that the length of yarn to be tested is hung from adouble-edged knife with a 500-gram weight for 2 minutes, wound aroundthe blade, and out along one edge after 10 minutes. llhe angles are letrelax for 10 minutes before measuring.

Seco n dary swelling is measured by wetting weighedskeins of untreatedand treated yarns aqueous ammonium hydroxide solution,

with water, centrifuging them together, and weighing each in a closedcontainer to determine the amountof water retained. The untreated yarnusually retains a quantity of water approximately equal to the weight ofthe yarn. The secondary swellingof treated yarn is expressed as per centrelative to that of theuntre'ated'yam. This untreated yam extendsspontaneously when wet with water until it is '40%-50% longer than whendry. v

The excellent uniformity of treatment-by the process of the presentinvention is apparent upon examination of skeins of the treated yarnafter dyeing with a direct cotton dye, On the other hand the same yarn,when treated with a water solution containing 8% of formaldehyde and025% of ammonium chloride, centrifuged, dried at 6575 C. for 2 hours,baked at 153 C. for 3 minutes in an oven, and dyed with-a direct cottondye, is colored very unevenly. This unevenness indicates "a verynon-uniform treatment.

EXAMPLE VII A skein of crimped viscose rayon yam like that treated inExample VI is impregnated with a water solution containing 3% offormaldehyde and 0.4% of ammonium chloride, centrifuged, and immersedfor 10 minutes in xylene heated to 138 C. The yarn is improved uniformlyby this treatment in resilience and wet strength.

Exsuru: VIII Skeins of crimped viscose yam like that treated in ExampleVI are impregnated with water solutions containing 0.4% of ammoniumchloride and the amounts of formaldehyde indicated in Table III,centrifuged, dried at-room temperature, immersed for the indicatedperiod of time in xylene heated to 138 C., and washed by the procedureof Example II. Results of the treatments are summarized in Table III;Dyeing tests show the treatments are all quite uniform. Whenbis(ethoxyethyl) ether is used instead of xylene, the results areequally favorable. This solvent has the added advantage of beingmiscible with water and, therefore, readily removable from the fabric.

Table III I Tim r In Qe Formal- Crease crease dehyde m" angle i inelon-2:53;, swelling Per can) Minutes Degrees Per cent Per cent Per cent None'66 1 l 70 13 32 $3 1 2 72 15 33 44 1 -87 35 as 62 2 2 105 92 58' 66 2 5108 72 53 80 3 1 113 81 '43 at 3 2 m 110 is 77 3 5 156 T5 61 l 89 5 l166 84 53 s2 5 2 180 55 -58 as 2 180 0 63 85 Exssnmn IX Gel staplefibers prepared by the process of U. 8. application Serial No. 180,976,referred to in Example VI are impregnated with a water solutioncontaining 2% of formaldehyde and 0.4% of ammonium chloride,centrifuged, and dried at room temperature. They are immersed for 5minutes in mineral oil heated to 145 C. and then thoroughly washed withsoap to remove the oil. The treated fibers show improved resilience andresistance to swelling in water. Dyeing tests show the treatment isuniform throughout. Fibers in staple form are particularly dimcult toheat uni formly in air.

' ExAm'LnX A rope of yarn of the type treated in Example VI .15impregnated with a water solution containing 2%.of formaldehyde and0.2%v of ammonium chloride, centrifuged, and dried at room thick to beheated uniform-1y throughout in a temperature. It is immersed for 5minutes in triethanolamine heated to 150 C. and then"- washed withwater. The treated fibers show uniformly improved resilience andresistance to swelling in water. Rope of this nature is too perature.They are immersed for 1 minute in Wood's metal heatedto 138 C., washedwith an alkaline soap solution, rinsed, and dried. Both treated skeinsshow uniformly improved resilience and resistance to swelling in water.

Exsurnn XII Transparent velvet having a viscose rayon pile and silkbacking is impregnated with a water solution containing 13% offormaldehyde and 0.4% of ammonium chloride, centrifuged, and placed inboiling benzene for 1 hour. It is then dried, 85

rinsed with warm dilute ammonium hydroxide solution, and soaped for 1minute at 70 C. with j Exsurns XIII- Samples-of transparent velvethaving a viscose rayon pile and silk backing are impregnated with awater solution containing 0.4% of ammonium chloride and 2% and 5% offormaldehyde, re-

spectively, centrifuged, and dried at room tem- ,perature. They areimmersed for 1 minute in and water, heated in dilute ammonium hydroxidexylene heated to 138 C., rinsed with methanol solution at 10C. for 3minutes, and then in an alkaline soap solution at 70' .C. for 3'minutes.

and rinsed. Both samples show improved resilience. Exsurnr XIV Viscoserayon yarn spun from viscose containing casein as described in BritishPatent No. 501,531 is impregnated with a water solution contairiina 3%of formaldehyde and 0.4 of ammonium chloride. centrifuged. and dried atroom temperature. It is immersed for 1 minute in xylene heated to 138'C. and then washed. The treated varn shows uniform y improvedresilience and wet strength and lowered elongation.

tetrachlorooctane,

dichloride,

As above set forth, if any formaldehydereactive textile material isimpregnated with aqueous formaldehyde and an acid-reacting catalyst,dried and then heated-byimmersion in a hot substantially anhydrousliquid which 5 is substantially inert to water under the conditionsprevailing during the heating step, an improved and-morev uniformlytreated product will be obtained. a

As a formaldehyde-reactive textile material, the present inventioncontemplates the treatment of filaments, yarns, fabrics and the like.comprising regenerated cellulose, regenerated, protein materials, andlow substituted cellulose esters and ethers; i. e., cellulose esters andethers having at least one unsubstituted hydrox'yl group.

The present invention is operative in the treatment of all textilematerials which are at all reactive to formaldehyde. In the treatment ofsuch textiles asare less reactive than those specifically referred toabove, the treating conditions will,'of course, be more drastic.

The term textile material includes fibers in the form of loose staple,yam, fabric, or finished article and filaments in the form of yarn,fabric,

or finished article. The fabrics may beknitted',-\

woven, or felted. They may be special'types of fabric such as pilefabrics or crepe. Viscose rayon fibers may be treated in the gel stateeither as staple, rope, or yarn.

The term "acid-reacting catalyst is intended to include water solublesubstances which are acid in reaction, or capable of becoming acid underthe conditions of the treatment, or capable of. liberating an acid underthe conditions of the treatment. Examples are organic 'carboxylic orsulfonic acids such as oxalic acid,

tartaric acid, and benzenesulfonic acid, acid salts of organic acidssuch as sodium acid 40 tartrate and potassium tetroxalate, mineral acidssuch as hydrochloric acid, sulfuric acid, and phosphoric acid. acidsalts of mineral acids 7 such as sodium bisulfate and dihydrogen sodiumphosphate, and salts of strong acids with'weak bases which dissociate inwater solution to give an acid reaction such as ammonium thiccyanate,anmionium chloride, "ammonium bromide, ammonium iodide, ammoniumsulfate, hydroxvlamine hydrochloride, ferric chloride, calcium chloride,aluminum chloride, 'etc. The catalyst chosen in any particular case willbe the one which is sui'llcientlypowerful to effect" the degreeof-chemfcal reaction desired between the textile material and theformaldehyde. Because of its cheapness' and effectiveness, ammoniumchloride lathe catalyst which is preferred in the exercise of thisinvention.

As liquids suitable for use as heating media in the prgaess of thisinvention, there may be usedany substantially anhydrous liquid boilingabove C. and preferably above C. which "is substantially inert to waterunder the conditions prevailing during the heating step. :Exarnpies arehydrocarbons such as benzene, toluene, 55

mlene, kerosene, mineral oil, high boiling benzine, triisobutylene,etc., esters such as. butyl acetate, tricr'esyl phosphate, dime-thylphthalate, Cellosolve? and Carbitol esters, butyl V borate, etc.,alcohols, such as glycerol, ethylene 7o glycol, butanols, octanols,etc., halides such as tetrachloroethylene, chlorobenzene, bromobenzene,tribromoethane, amylene chloronaphthalene, chlorotoluene,

dicblorobenzenes, etc., hydroxy ethers suchas 7 Cellosolves andCarbitols, ethers such as diisobutyl ether, bis(methoxyethoxyethyl)ether, and dioxane, amines such as monoethanolamine, diethanolamine,triethanolamine, dimethylaniline, etc., and low melting metals or alloyssuch as Woods metal, Rose metal, and mercury. The organic liquids usedmay be aliphatic 'oraromatic, saturated or unsaturated. Of -course,esters and ethers which are solvents forcellulose esters and etherscannot be used as heating media in treating textile materials composedof the latter substances. In any case the liquid used should preferablybe easily removed from the textile material, stable toward heat, inerttoward water, non-toxic, and non-flammable. Bls(methoxye thoxyethyl)ether and bis(ethoxyethyl) ether are preferred heating liquids incarrying out the'present invention.

The formaldehyde treating solution maycontaln desiredmodifying agentswhich will improve the resulting product, as long .as the modifyingagent does not interfere with the reaction between the formaldehyde andthe textile material. For example, long chain agents such as glycerolmonostearate or sulfonated castor oil may be added to the formaldehydesolution to improve hand and feel of the textile material. However, whensuch a long chain agent is used and the liquid heating medium used is asolvent for it, it is preferable to saturate the liquid heating mediumwith-the long chain agent so that the agent will be retained by thetextile material and not dissolved out by the heating medium. r

" The concentration of formaldehyde to be used in the treating solutionvaries, of course, with the material under treatment, the nature andconcentration of the catalyst, the nature and concentration of modifyingagents, the conditions of drying and heating, and the effect desired.For example, for creaseprooflng viscose rayon a higher formaldehydeconcentration is required than for shrinkprooflng the material, otherconditions remaining the same. Generally, when the drying and heatingconditions are more severe, that is, when higher temperatures and longertimes are employed, less formaldehyde is required. Thus, if theimpregnated ma: terial is dried at 100 C. rather than at roomtemperature, less formaldehyde will be required to give the same finaleffect. Generally, -to obtain comparable. effects, less formaldehyde isrequired when a more strongly acidic catalyst is employed or when acatalyst is used in higher concentrations, than when a more weaklyacidic catalyst is employed or when a catalyst is used inlowerconcentrations. Usually, a concentration of formaldehyde of atleast 1% is required to obtain a-noticeable effect on cellulosic.materials. The upper limit is the concentration at which the particulartextile material being treated is made too weak or too brittle for use.As a general rule, the formaldehyde concentration should not exceed 20%.With these facts in mind, one skilled in the art can readily determinethe concentration of formaldehyde which will give optimum results undera given set of other conditions.

The catalyst concentration may vary from as low as 0.05% or lower to ashigh as 1% or higher depending on the potential acidity of the catalyst,

the nature of the textile material under treatment the concentration offormaldehyde employed, the nature and concentration of modifying agents,the drying and heating conditions,

and then squeezed temperature to 150 C. or higher.

and the effect desired. Other conditions remaining the same, an increasein the catalyst concentration or a change from a less to a more stronglyacid catalyst results in a greater degree of modification of the textilematerial. Usually, the selection of the nature and concentration of thecatalyst is a matterof balancing catalyst efilciency against tenderingwhich results from the use of acidic materials on many textilematerials, particularly celiulosic materials. By reference to the aboveexamples and the following description one skilled in proper catalystand concentrationto bring about the desired result- The treatingsolution may be applied to the textile material in any of several ways.Staple fibers may be dipped in the solution and squeezed or centrifugedto remove may be passed continuously through the solution or it maybedipped in skein form in the solution or centrifuged to remove excesssolution. Flat fabrics may be passed through the solution or thesolution may be applied from rolls or by spraying and the excess may beremoved by squeezing between rolls orby vacuum extracting. Articles, asof clothing, may be dipped in the solution or sprayed. Fabrics orarticles of clothing may be treated locally by spraying.

The formaldehyde and catalyst may also be applied in other ways. Forexample, the textile material may be wet with a solution of the catalystand then exposed to vapors of formaldehyde, or it may be Wet withformaldehyde solution and then exposed to a gaseous catalyst such ashydrochloric acid.

After impregnation with the treating solution the textile material ispreferably dried to a water content of about or less before it issubjected to the final heat treatment. This may be carried out many ofseveral ways. It maybe dried in air or in a heated inert liquid such asa hydrocarbon or ether. If it is air dried, the temperature of dryingmay .range from room high temperatures in air must be carried out withcare so that no part of the textile material is heated after it is dry.Uniformity is favored by vigorous circulation of air in the dryingchamher and by use of temperatures below 100 C., and preferably below 50C. The most uniform drying, particularly for staple, large skeins ofyarn, and garments, is obtained by use of a hot the art can readilyselect the- Drying at 2,a11,oso

excess solution. Yarn material under treatment is'in a relatively loosecondition so that air will circulate through it freely, air drying hasan advantage over drying in a hot liquid in that the formaldehydeconcentration required for a given degree of modification is much lowerand the overall period during which the material is held at. the higherliquid temperature is shorter, so that the risk of tendering due to theeffect of the acid reacting catalyst at high temperatures is less. Athigher temperatures the liquid drying method is generally more rapid dueto more eflicient heat'transfer between the moisture and the heatingmedium. If, for example, a liquid such as molten metal is used at atemperature in the range of from 200-250. C. or higher, drying may oecomplete in a fraction of a second. In general, with other conditionsremaining constant, an increase in the drying temperature leads to agreater degree of modification of the textile material.

In orderto bring about areaction between formaldehyde and the textilematerial within a reasonable time, it is necessary to heat theimpregnated and driedmaterial. In this process the heating step iscarried out by immersing the textile material in a hot liquid of thenature disclosed above. The temperature of the liquid may be as low as'l0 C. or lower, althougha much longer heating period is required atsuch low temperatures. As already pointed out, if a heating temperaturebelow 100 C. is used, that temperature should be the boiling point ofthe liquid so that water formed by the reaction will be removedemciently. The temperature of the liquid may range as high as 200 C. oreven higher. However, it should be emphasized that at such hightemperatures the heating period modifying agent, thetemperature ofdrying, the

time of heating, the effect desired,and the nature of the textilematerial under treatment.

A It is common knowledge that some textile materials are moresusceptible to damage by heat than are others and so require morecareful treatment in any heating process. In general,

with other conditions remaining constant, an increase inthe temperatureof the heating liquid leads-to a greater degree of modification of thetextile material under treatment.

inert liquid in which water is preferably no more than slightly soluble.Liquid temperatures up to 250 C. or higher may be used. If a temperaturebelow 100 C. is used, it .is usually necessary to boil the drying liquidin order to carry out-the water. Consequently, for drying at suchtemperatures liquids boiling below 100 C. are desirable. However, ifthey boil below about C. the rate of drying will generally be too lowfor practical purposes.

The time of drying depends, of course, on the drying method used. Whenthe air drying method is used, the time required depends onthetemperature, circulation of air, and the relative thickness andlooseness of the material under treatment. When the hot liquid dryingmethod is used, the time required depends on the nature of the liquidand the temperature used and less on the construction of the materialunder treatment. In general, with temperatures below 100 C., the airdrying method is more rapid and may require as short a time as 2minutes. When the "Cline heat ng per od may be varied from as long as anhour or more at low temperatures, such as 70 -80 C. or lower, to afraction of a second at higher temperatures. such as 200 C. .or higher.When the heating is to be carried 'on over a period of about a minute orlonger it is advantageous to place the textile material in a perforatedcontainer which is lowered into the hot liquid bath and then liftedafter the desired length of time. When yarn or fabric is to be heated at.a higher temperature {for a shorter period oftime, it is advantageousto pass the yarn or fabric continuously through the heating bath at arate depending on the length of bath travel. With other conditionsremaining constant, an increase in the heating period leads to agreater'degree of modification of the textile material under treatment.

From the above descriptions, it will be apparent that the dryingstep'and the heating step may be combined into one continuous step. Thedrying liquid may be used for the subsequent heat treatment. Thus, it issometimes convenient to prolong the period of immersion in the dryingliquid until the reaction between formaldehyde and the textile materialhas proceeded to the desired point.

After the heating step it is usually desirable to remove theheatingliquid. This may be accomplished simply by evaporation of the liquid ifthe liquid is sufllciently volatile, benzene, for example. If the liquidis water soluble, triethanolamine, for example, it can be washed outwith water. Water insoluble non-volatile materials may be displaced by avolatile or water soluble solvent or removed by soaping. It is usuallydesirable to neutralize any traces of acidic material which may be leftin the yarn by washing with a solution of ammonium hydroxide or othermildly alkaline material. The treated material may then be finishedinany desired manner such as by application of a softening agent orwater repellent agent.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the present invention, it is to be under-' stood that the inventionis not to be limited to the said details except as set forth in thefollowingclaimsw 1 I claim:

1. In a process for reacting a textile material with formaldehyde, thesteps comprising-umpregnating said material \with an aqueous solution offormaldehyde, drying said impregnated material, and heating the same toreaction temperature by immersion in an inert heating liquid at atemperature of between 70 C. and 200 0., whereby said materialisuniformly reacted with the formaldehyde and objectionableembrittlement thereof is prevented.

2. In a process for reacting a textile material with formaldehyde, thesteps comprising im-' pregnating said material with an aqueous solutionof formaldehyde and an acid reactingic'atheating liquid at a temperatureof between 70 C. and 200 0., whereby said material is uniformly reactedwith the formaldehyde and objectionable embrittlement thereof isprevented.

4. In a process for reacting a regenerated cellulose textile materialwith formaldehyde, the steps comprising impregnating said material withan aqueous solution of formaldehyde and an acid reacting catalyst,drying said impregnated material, and heating the same to reactiontemperature by immersion in an inert heating liquid at a temperature ofbetween 70 C. and200 0., whereby said material is uniformly reacted withthe formaldehyde and objectionable embrittlement thereof is prevented.

5. In a process for reacting a regenerated cellulose textile materialwith formaldehyde, the steps. comprising impregnating said material withan aqueous solution of formaldehyde, dryingsaid impregnated material,and heating the same to reaction temperature by immersion in .a liquidcomprising a hydrocarbon, whereby said material is uniformly reactedwith the formaldehyde and objectionable embrittlement thereof isprevented.

6. In a process for reacting a regenerated ceilulose textile materialwith formaldehyde, the

alyst, drying said impregnated material, and

heating the same to reaction temperature by immersion in an inertheating liquidat a temperature of between 70 C. and 200 (3., wherebysaid material is uniformly reacted with the formaldehyde andobjectionable embrittlement thereof is prevented. l

3. In a process for reacting a regenerated cellulose textile materialwith formaldehyde, the steps comprising impregnating said material withan aqueous solution of formaldehyde, drying said impregnated material,and heating the same to reaction temperature by immersion in an inertsteps comprising impregnating said material with an aqueous solution offormaldehyde, dry

ing said impregnated material,and heating the same to re'actiontemperature by immersion in a liquid comprising xylene, whereby saidmaterial is uniformly reacted with the formaldehyde and objectionableembrittlement thereof is prevented.

7. In a process for reacting a regenerated cel.-.

lulose textile material with formaldehyde, .the steps comprisingimpregnating said material with an aqueous solution of formaldehyde,drying said impregnated material, and heating the same to reactiontemperature by immersion in a liquid comprising bis(ethoxyethyl) ether,wherebysaid material is uniformly reacted with the formaldehyde andobjectionable embrittlement thereof is prevented. i

8. The process of decreasing the secondary swelling of substantiallynon-crenulated and non-oriented, permanently crimped, regeneratedcellulose filaments which comprises impregnating a textile materialcomposed of said filaments with an aqueous solution of formaldehyde,drying said impregnated material, and heating the same to reactiontemperature by immersion in an inert heating liquid at a'temperature ofbetween C. and 200 C.

PAUL 8. PM.

